Right now I am using the 3DVIA composer TRIAL software (the lastest version) and I'm facing an issue. I am trying to make black and white images using the silhouette rendering mode, and then saving them as JPG or similar format. Problem is, the images look really bad. The lines look transparent. Is this a problem because I'm using the trial version?

Also, do any of you have any good tips for making cables in 3DVIa composer? Easily?

I use 3DVIA and can try and help you but I need a little clarification. If you are trying to get black and white you should be using Technical Illustration mode and choosing options from there. Silhouette per object is an option but saving as a .jpg is not. You should save as a .svg or .eps for vector graphics. The trial version should not be effecting your export. If you want to post a screen shot I can take a look at it for you.